Torque wrench



Patented May 23, 1939 PATENT oI-Flcs TOBQUE WRENCH f y Allen I. Dunn.Cedar Rapids, Iowa, assigner to Engineering Cellar Rapids Oompany, CedarRapids, Iowa, a corporation of Iowa Application October 28, 1937, SerialNo. 171,506

Claima.

This invention relates to wrenches. and more particularly to a wrenchfor indicating the amount of force or torque applied to the handle inrotating or attempting to' rotate a nut or the 5 like engaged by thewrench.

This application is a continuation in part of my application Serial No;136,048; flied April l0, 1937.

It'has been found. for instance, in the tightening of nuts on cylinderheads of internal combustion engines, or in assembling precision devicessuch as air-craft engines and the like, that it is very desirable totighten the nuts and bolts of such devices to certain known degrees.

It' is a general objectl of my invention to provide a mechanical torquemeasuring wrench in which deformation of the parts of the wrench isemployed in indicating the torqueapplied to the wrench.

I0 It is also an object of my invention to provide a wrench of the abovecharacter in which the parts are protected from mechanical injury.

Another object of my invention is to provide a torque indicating wrenchof extremely simple 25, construction and in which there is a minimum offriction. 1

Another object of my invention is to provide a torque indicating wrenchof increased accuracy n over devices known to the prior art.

' Another object of my invention is to provide a torque indicatingwrench in which the operator, in using the wrench, grips the wrench atone point only so that the readings are always accuu ratek ad correct. f

Another object of my invention is to provide a torque indicating wrenchin which the torque measuring instrument is located in a position whereit is out oi' the way when engaging the n vrk and where it is protectedfrom mechanical 1 ury.

Other and further features and objects of the invention will be moreapparent to those skilled in the art upon a consideration of theaccompanying drawing and following specification,

wherein is disclosed a single exemplary embodiment of the invention,with the understanding, however, that such changes may be made thereinas fall within the scope oi' the appended claims,

50 without departing from the spirit of the invention.

In the drawing:

Figure 1 is a plan view of a wrench constructed according to a preferredembodiment of 55 my invention.

Figure 2 is a view in vertical section through the wrench shown inFigure 1, and

Figure 3 is a view in horizontal section through the wrench shown inFigure l.

A device constructed according to a preferred l embodiment of myinvention includes a head Il, in which a ratchet shaft or socket shaftII is received, and this head serves also as a means for receiving ahollow handle I2 at right angles to the socket handle shaft II. Theopposite end l0 of the handle I2 is received in an indicator base Il. Agrip lia comprises an extension of the indicator base Il and anindicator Il is received in the indicator base L.

In the form of the device here shown, I have u incorporated a ratchetmechanism in the head III. This ratchet mechanism includes a ratchetwheel Il having square teeth II. The pawls Il and Il are received inbores 2| and 22 which are formed in outwardly flared portions IIa andIlb so of the head I0. These pawls are so arranged that when one of thepawls is in engagement with a tooth as indicated at 2l, the other pawl24 is riding on top of the tooth. Thus, half steps of ratchetlng aresecured. 25

The pawls I 8 and Il are biased inwardly by means of springs 26 and 2'Iwhich bear against the pawls Il and I9 and against caps 2l received inthe cylindrical bores 2| and 22. Pins 29. having knurled heads SI, havea threaded engage- 30 ment with the pawls II and I9 and the pawls may berotated by means of these knurled heads 2| so that the ratchet wheel Itmay be rotated in either direction as desired by oscillating the handleI2 or may be locked with reference to the 3- head I0. A squared end Ilais provided on the end of the ratchet shaft II to engage sockets inaccordance with the usual practice.

A split sleeve l2 is received within the handle I2 within the head I0and this split sleeve is o anchored to the large end of a tapered shaftJ3, this shaft 3l being of course, located within the hollow handle I2.'I'he shaft is tapered so that a maximum of clearance between the shaftand handle is afforded at the free end of the shaft. The hollow handleI2 is made' of resilientmaterial, as will hereinafter appear. Onelocking means for locking the split sleeve 32 with reference to theshaft ll is a set screw and ball indicated at Il.

When the set screw n in the head III is screwed tightly into placeagainst the hollow handle I2 it not only holds'that member in place butdefor'ms it enough to grip and hold rigidly the split sleeve 32 and theshaft I3. 55

videdwitna'sput misma 'cess-to me cnambenlmy be ima g -transversebore 4|which passes through-the indicator base il. The bore 4i may be closed bythe threaded plug'4l. v

A movable cylindrical portion |44 of vthe indicator I4 is re'ceivedwithin the bore 4I` and is .'held in place by va ball and springinserted through the base il and abutting against the.

cylindrical portion I4a. Thesprlng tensionl may be changed by means o!va screw which holds the spring and ball in place, thus allowing theindicator to be set at aero, all in accordance with the usual practice.The shell I4b of the indi- Y cator abuts against the outer face of thebase il. The gear rack 81 engagesa pinion 42 located -on the pinionshaft 4I and the pinion shaft 43 is rotatably mounted in bearings 44.

"An indicator needle 4l is secured to the outer end of the shaft 44 vandof course rotates over the .dial 4l in accordance with movement of thefree v end vof theshaft 33 with reference to the indicator basey I I. Ahair'spring 4l is provided to 1 vtake up any lost motion or backlashbetween the pinion 42. and rack 31. l

It -may readily be understood that iffthe sockv"et handle lia is engagedon a socket and the socket engaged to a nut, bolt or the like andpressure applied to the'handle lia. the flexible handle i2 willmove withVreference tothe shaft. 3l. If the direction of the force applied is atIright angles to the axis of thesocket handle Il, j the relative movementof the handle with referen'ce to the shaft will cause thegear rack 31..to rotate thepinion' 42to cause movement ofv 'the indicator needle 45over the dial 41.

.a nut. In lcalibrating the dial 41,v the distance The grip Ila is' soformed and arranged that it constitutesthe handiest place for theoperator to grasp the wrench in tightening or loosening from the centralportion of the grip Ila to the centerv line of the socket handle Il maybe considered the lever arm for rotating the handle.

-The dial may4 then be calibrated with markings Lcorresponding to thenumber of inch-pounds-applied at the grip Ila, the number of inches be-1 ving considereda's the distance from the center ofthe grip to the axisof the handle Il. 'Obviously the dial may be calibrated in any suitable:manner as in inch-pounds, foot-pounds, centimeter-grams or any otherunits of measure--l g ment.

new

set forth in th'eappendedciaims. my invention:

shaft to theindicating means for driving indicating means. v g

l il.` In a torque indicating wrench, `\a head, a

viiexible hollow handle 'xed to the head, a grip' member having anopening transversely therethrough, the grip member being ilxed to thehandle, an indicating device mounted within-y the opening, a Ashaftcoextensive with the handle and located within the handle, means forrigidly engaging the shaft at the head end of the wrench and a rack andpinion for 'driving the indicating devicefromthe free end of the shaft.l

3. In a torque indicating wrench, `a head, a flexible hollow handlesecured lwithinthe head, a grip member at the other end of vthe hollowhandle, an indicating means mountedwithin the grip member, a shaftcoextensive with the handie and secured within the handle and head, and

means for operatively connecting' the indicatin means with'the free en dof the shaft. l,

v4.'In a torqueindicating wrench. a head, a

nut engaging means on the head, a nexible hol,

lowhandle `engaged to the head, a sleeve within the hollow handle andthe head, a shaft engaged within the sleeve, a grip member mounted onthe opposite end of the hollow handle'from the head, an indicating meansmounted within the grip member, and a rackand gear for driving theindicating means from the free end of the shaft. l

5. In a torque indicating wrench, a head, a

iiexible hollow handle member fixed-to the head,

an instrument base on the flexible handle member opposite to the head, ashaftrigidly engaged 4within the head and extending through the handle,an indicating means mounted in the instrument base, and geared means fortransmitting relative movement between the free ends of the shaft andlhandle to. the indicating means to indicate the relative degree of vsuchmovement.

I. DUNN.

